Three-dimensional adapter for motion-picture projectors



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THREEDIMENSIONAL ADAPTOR FOR MOTION-PICTURE FROJECTORS Filed Nov. 4, i947 4 sheets-sheet 1 Aj, Juf.

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THREE-DIMENSIONAL ADAPTOR FOR MOTION-PICTURE PROJECTORS Filed NOV. 4, 1947 4 Sheets-5heet 5 INVENTOR. 05557- l/. @EEN/EE HTTENEYS i6, 1949. R. v. BERNIER 'l 72,478,891

THREE-DIMENSIONAL ADAPTOR FOR MOTON-PICTURE PROJECTORS Filed Nov. 4, '1947 4 sheets-sneet 4 INVENTOR. l v ,6055er V. 5 EN/Ee www' @goe/Veys Patented ug. 16, 1949 d4 Claims.

The .invention describedherein may-.be manufactured and used by orforthe.Government for governmental purposes .Without payment `to me of any royaltythereon.

This invention relates `toen vattachment for a motion Ypicture projector ,by .means .of which .a standard motion pictureA projector. is made available for projecting threeedimensional lrns.

.An object of .the `inventionis to .provide vfor the above purpose a simple .attachment which is instantly removable, and, when.1emoved,'leaves no obstruction which may ,interfere ,with the operationpf 'the tprojector as used in standard practice,

Another object 4is to provide a polarized fiiier operated by the movement of the lin and synchronized by vthellatter Ato the movement Aof .each frame.

Another object is to provide a Apolarized ilter of cyiindrica'l or semicylindrical contour which may be rotatedby Ymovement of thefilm, thecylin'der'being polarized in such a manner'that polarization is reversedat each 'half 'turn jof the cylinder.

Another object .of '.the invention is vto 'provi-:le acylindrica'l orsemiylindricalliilter, so polarized that,V inrevolving, it''first polarizes ,a franrein a direction 'forty-five degrees upward and 'to "the left-andthe next frame'in a directonvlfoijty-ve degrees upward and to theright.

Another. object is to provide a 'mechanism which pernits adjusting :the ,synchronization of the polari ation to successive'lirarnes.

Another object is 'toprovide means forjinter changing theplarization of alternatefframes Other objects arid-.advantages,willbecome levident as theinvention ,described indetail with reference .to .tlie.drawings, wherein:

Fig. 1 is a schematic..illustrationshowing hou/.a seinicylindrical lter ispolarizedso as -to reverse the polarity at each halt-turn-of the cylinder.

Fig. 2 is a-view similar to Fig. l exceptthatlthe film has been advancedcneframe-and thegsemicylindrical lter has Abeenturned'one hundred eighty-degrees. f

Fig. 3 is a schematicseetionalrview ofthe semicylindrical lter tand Aits, driving fmechanism ,as seen on the line.3.3 ofFigA.

Eig. 4 is a schematic-.Viewshowingithe; arrangement of .the semicylindrical filter. with .respect toparts of thestandard projector.

Fig. 5 is a perspective viewpf.analternatelter which consists of a complete cylinder :gcomilcsed f WO Semiylillders .nf .transparentxmaterial fthe 'amended April :'30, 1923;".3702411 "I o'.)

twofsemicylindrical halves beingpularized in .oppositclyihelical lines.

6.is-aperspective .View .ofthe lter-shown in Fig. 5 after the cylinder .has .been rotated on its -,axis `onequarter turn, illustrating h ow the 4polarization in -ppposite 'halvespf .the .cylinder coincide .when ,the lens .axis .passes through .the mid p oint-.of the ltwo halves,

Fig. .7 .represents the .saine cylinderfafter iit has been rotated on zits axis .one-,half zturnirom the position seen in Fig. 6.

.-Fg. 8 .is .,a perspective `view -pf :the .bracket which .is ,secured -to ,a .standard gpiojector for holding .the .attachment ,in Kloperating 1 position.

.-Fig.,.9sisa perspective view-of the attachment which .is the `.subject oi :this invention.

Fig. .10 shows .thefattachment in ;.p1ac e on :a standard projector.

.Like .reference .characters refer to .like lparts throughout .the .several -views.

.The .invention :herein .disclosed `requires that three-.dimensionallm be used with the rightand leftstereoscopic 4images .spaced .alternar/ely, .and thatthe .viewers of thefpicture weanconventional three-dimensional Polaroid spectacles.

,InFig. 1,;1ight -froni a ,source l0 is allowed to Dass .consecutively through a v:dim ,I 2, .-a. `lens .4 andialter ,Il B tp -thescreen .[8. Thefflm .-i 2 ,is of the three-.dimensiona1-type wherein the right and .thelleitistereos-copic:images are Aspaced alternately. .The 4lter .i6 lis `seinicylindrical and positioned tobe rotatedonitsaxis which .prefere ably is inthe same,plane.as butnormalto the lensaxis. 'Polarization 2D .of thesemicylinfier when lviewed from the outside is at forty-,five degrecs upward ,and totheleit, ..,e., as in a fortyvedegree external ,righthandhelx Afrazne 22 having Va fleft stereoscopic irnage .therein ,is centered on the lensaxis. 'Ihe image ,2,4 onthe screen I Bmay beseen with .the ,left eyeonly ,by a viewer wearing ustandardPolaroiiispectacles.

"InFigjZythenim .IZhas beenadvanced so that aiframe-z "having a right stereoscopic -image thereon is'centered 'on :the lens axis While the filter i6 has beenzrevlved -one Ahundred eighty degrees V'from the jposition it occupied .in I ,1. It-is-noted-that,inFig-ljthe outside ofthe semicylindrical lter 16 is presented 'cto the lens ,1;4 while in` Fig.' 2 theinsde of thesemiylindric-l 1terispresentedto the lens '|4. 'Moreovenlthe same -lines l"Ml ofpolarization which injFfig. 1 eX- tended upwardly and to thejleit, ,nowextend upwardlyandlto'the right. The image '28 on the screen I8 may'be seen-With the right eye'onlyfby aliviewer wearing standard'Polaroid spectacles. It lwill .be :evident that, iby employing -fllm the cipal requirement for three-dimensional motion pictures.

Figs. 1 and 2 merely disclose the principle upon which the invention operates. Figs. 3 and 4, however, illustrate, more or less schematically,

4 relative to Figs. 1 through 4. The alternate cylinder may consist of a single piece polarized as shown in Fig. 5 or it may comprise two half cylinders lG and 'E8 held together in any suitable manner.

If a cylindrical filter, having been polarized as seen in Fig. 5, is rotated one-quarter turn in the direction of the arrow 88 to the position seen in Fig. 6, polarization viewed along the line 82 the principal parts of the mechanism employed and the cooperation of the parts in carrying the invention into effect.

Referring more particularly to Figs. 3 and 4, a semicylindrical lter 6 may be made by bending a sheet of thin transparent material to semicylindrical form and holding the sheet to that form by means of circular inner and outer end heads 3G and 3.2 which contain semicircular grooves for securing the edges ci the filter. The edges of the lter may be retained in the grooves by any suitable cement. 1

A shaft 34 carrying a pinion 36 is drivably connected to the end head 30. A casing 38 has a short sleeve 40 extending rearward for joining to the lens holder 39 and another sleeve 42 eX- tending forward for passing the light to the projector screen i8. Sleeves 40 and 42 are centered on the axis of the lens.

A standard eight tooth nlm sprocket 44 is fast on the shaft 46 which is rotatably supported in a bearing d8 carried by the framework 5D of the attachment. A gear 52 is also fast on the shaft 46 whereby the sprocket 44 and gear 52 rotate as one. An idler gear 5.4 connects the gear 52 to the pinion 36. 1

4Concentric with but independently rotatable with respect to the sprocket 44 and gear 52 is a gear 56-(See Fig. 4) which carries a stud 58 near its periphery upon which a lm guide idler pulley is freely rotatable. A pinion E2, perma nently meshed with the gear 53, is manually rotatable bythe knob E4, whereby the stud 5B may be moved in the direction of the arrow 65 or the arrow 58 to respectively lengthen or shorten'the nlm loop lil, whereby the sprocket 44, and consequently the semicylindrical filter l5, will be advanced or retarded, with respect to the projector drive sprocket l2 which maintains synchronism with the,v movement of the lm by the shuttle mechanism (not shown) through the lm gate 14. The' ratio of the gear 52 to the pinion 35 is preferably such that one eighth turn, i. e., a movement of one tooth span of the attachment sprocket 44, which equals one frame of the film', will require about one sixteenth turn of the adjusting gear 5G. This will rotate the semicylindrical filter i6 through one-half turn, whereby.

polarization of filter i6 with respect to any frame of the film I2 is reversed. Thus the increase or decrease of the length of lm between the projector sprocket 72 and the attachment sprocket 44 of one frame permits interchanging the polarization of the right and left images should a scene on the film be spliced with the frames improperly sequenced. Adjustments of lesser amounts facilitate bringing the filter into coincidence with its proper frame when the off condition amounts to part only of a frame.

Figs, 5through 7 show an alternate method of reversing polarization by using a. filter compris-- ing a complete cylinder of transparent material instead of the semicylinder heretofore disclosed Gili will be upward and to the left in both iront and rear halves TG and T8, while if the filter is then turned an additional half turn to the position seen in Fig. 7, polarization will be upward and to the right. Obviously a filter constructed as in Figs. 5 through l may replace the lter i8 shown and discussed with reference to Figs. 1 through 4.

In order to provide, for the attachment herein disclosed, a means to quickly aix or remove the device to or from a standard projector, a bracket 8E., Fig. 8, is provided and permanently secured to the body of the projector in such a position that it will not interfere with any of its normal functions. The bracket Sil includes a bar which may preferably be of square or rectangular cross section upon which the attachment may be supported in proper position. The bracket 84 is shaped and otherwise adapted for permanent attachment to the Ampro 16 mm. sound projector but obviously may necessarily be otherwise shaped and adapted for attachment to other sizes and makes of projectors.

The attachment assembly, the operating parts of which have been shown and described with reference to Figs. l through 4 is shown in perspective in Fig. 9, which, in addition to some of the operating parts already described includes a guide portion 88 having an opening 9S which is slidableover the bar 85 to which it may be xed against endwise movement by a screw 92 in the position Wherey the short sleeve S0 of the casing 38 makes connection with the lens holder 39 (see Figs. 4 and l0).

Having secured subject attachment to a standard project-or, the iilin is threaded in the usual manner except that. instead of proceeding from the upper reel 94 directly to the projector sprocket 'I2 (see Fig. 4) it passes first under then over the attachment sprocket dil and guide pulley G5 respectively.

If, after threading the nlm l2, it is found that the hlterl I G is out of registry with a frame of the film, a slight turn of the knobI 64 will eiect registry. If it is then found that the polarization of alternate frames is the reverse of what it should be, that may be corrected by turning the knob 0f. to such a degree as will advance or retard the lter one-half turn with res-ect to the projector feed sprocket l2. Such adjustment may be made before or during projection.

Aside from simplicity in general construction, the attachment herein disclosed has a considerable number of advantages: (l) Employing motive power taken from the lm sprocket "z2 of the standard projector and transmitting it through the nlm itself to the driving sprocket t4 of the attachment, obviates the necessity of a belt drive or similar power transmitting element. (2) Simplicityin obtaining a. ninety degree diierence in the polarization of the projected right and left image on the screen by the use of a rotary polar-i izer as compared with such patented features as mirror beam splitters and mechanically synchronized shutter arrangements. (3l Single beam projection which eliminates screen registration adaptation to many typescofprojectors.

1 Having describedmy inventionJ claim:

1. Motion .picture projecting equipment which j comprises, in combination, a` projector. including a lens, a film comprising a. series of frames in l' place in said projector in back of said. lens,V the frames of said lm having right and left stereoscopic images spaced alternately, a semi-cylindrical transparent polarized filter in front of said lens having itsaxis of rota-tion in the same plane as the axis of said lens but normal to. the. axis ofl 'said lens, polarization of the outside of saictlter :being in thedirection of a Arighthand helix, whereby whenthe'midsection of the semicylindricalV surface passes through the plane ofthe .cylinder and lens -axes withfthe outside of the cylindrical surfaceftoward the, lens, polarization of the semicylindrical surface will be upward and to the left, and when the midsection of the semicylindrical surface passes through said plane with the inside of said cylindrical surface toward said lens, polarization of said sernicylindrical surface will be upward and to the right.

2. Motion picture projecting equipment which comprises, in combination, a projector including a lens, a film comprising a series of frames in place in said projector in back of said lens, the frames of said film having right and left stereoscopic images spaced alternately, a semicylindrical transparent polarized lter having its convex surface in front of and facing said lens and having its rnidsection on the axis of said lens and its axis of rotation in the same plane as the axis of said lens but normal to the axis of said lens, polarization of the outside of said flier in this position being upward and to the left, whereby, when the midsection of the semicylindrical surface is turned on its axis through one hundred eighty degrees from said position, polarization of said semicylindrical surface viewed from said lens will be upward and to the right.

3. For use in connection with motion picture projecting equipment consisting of a projector including a lens and a film comprising a series of frames in place in said projector in back of said lens, the fra-mes of said film having right and left stereoscor'i'c images spaced alternately, the improvenie' it which comprises a semicylindrical transparent polarized lter located in front of said lens and having its axis of rotation in the same plane as the axis of said lens but normal to the axis of said lens, polarization of the outside of said filter being in the direction of a righthcoid helix, whereby who: the midsection of the semicylindrical surface passes through the plane of the cylinder and lens axes with the outside of the cylindrical surface presented to the lens, polarization of the semicylindrical surface will be upward and to the left and when the midsection of the semicylindrical surface passes through said plane with the inside of said cylindrical surface presented to said lens, polarization of said semicylindrical surface will'be upward and to the right.

4. For use in connection with motion picture projecting equipment consisting of a projector including a lens and a film comprising a series of frames in place in said projector in back of said lens, the frames of said film having right and left stereoscopic images spaced alternately, the im- \f.'.provement which .comprises a lA semicylindrical' transparent polarized filter having its Yconvex su." surface. turnedtoward said lens and. having its axis of. rotation in the same plane as the axis f 5 .said lensbut normal to the axis of said lens, po-

larization of the said filter in this position .being upward and to theleft, whereby, when the mid- -;;section of the semicylindrical.surface is turned 'fxfonehundred eighty degrees from said position, 10.'.l polarization of. said semicylindrical surface will .be upward and to the right.

Foriuse inconnection with motion picture projecting equipment.. consisting of a projector L-.' including. a'. lens anda nlm comprising a series l5 of .frames inplace in said projector in back of i: saidlenS, valternate frames having rightand left stereoscopic. images ithereon, the improvement whichicornprisesga transparent polarized iilter if inthe form ofa segment of a hollow cylinder zorhavlng itsconvex surface turned toward said lens si; and having its axis of rotation normal to the axis of said lens and approximately in the same plane as the axis of said lens, polarization of the said filter in this position viewed from the lens being approximately along a forty-five degree helix,

vliereby, when the convex surface is rotated substantially one hundred eighty degrees from said position, polarization of said filter viewed from said lens will be along a forty-five degree helix of opposite hand as the rst said helix.

6. For use in connection with motion picture projecting equipment which consists of a projector including a lens and a film comprising a series of frames in place in said projector in back of said lens, alternate frames having right and left stereoscopic images thereon, the improvement which comprises a transparent polarized filter in the form of a segment of a hollow cylinder having its convex surface turned toward said lens and having its axis of rotation substantially normal to the axis of said lens and approximately in the same plane as the axis of said lens, polarization of said filter in this position being along a helix, whereby, when the convex surface is rotated substantially one hundred eighty degrees from said position, polarization will be along a helix of opposite hand.

7. The structure defined in claim 6 with means for rotating the polarized filter in synchronism with the movement of the frames of the film.

8. The structure defined in claim 6 with means for rotating the polarized lter through approximately one hundred eighty degrees for each advance of one frame of the film.

9. The structure dencd in claim 6 with power transmitting means operable by movement of the film for rotating the polarized filter through approximately one hundred eighty degrees for advance of one frame of the film.

10. The structure defined in claim 6 with a film sprocket, power transmitting means drivably connecting said film sprocket to said filter, and means to vary the length of nlm between said sprocket and said projector.

11. The structure defined in claim 6 with a film sprocket, power transmitting means drivably connecting said film sprocket to said filter, a member concentric with but rotatable independently of said film sprocket, a film guide means carried by said member spaced radially outward from the axis of said film sprocket and manual means to rotate said member whereby the film length between said film sprocket and said projector is altered and the relation between said lter and the frames of said lm in said projector is adjusted.

12. The structure defined in claim G with a nlm sprocket having an axis parallelly spaced from tne axis of the lter, power transmitting means drvably connecting said sprocket to said filter, a gear concentric with but independently rotatable with respect to said sprocket, a stud positioned on said gear radially beyond the periphery of said sprocket, a film guide roller rotatable on seid stud and a manually rotatable pinion in mesh with said sprocket then around said lm guide roller then to said projector.

13. For use in connection with motion picture projecting equipment which consists of a projector including a lens and a lm comprising a series of frames in place in said projector in back of said lens, alternate frames having right and left stereoscopic images thereon, the improvement which comprises a transparent lter in the form of a hollow cylinder half of the circumference 14. The structure defined in claim 13 with means for rotating the polarized lter one-half turn for each movement of the lrn a distance of one frame. l

' ROBERT V. BERNIER.

REFERENCES crren The following references are of record in the le of this patent:

I FOREIGN PATENTS Number Country Date L282,331 Great Britain Mar. 28, 1938 555,670 Great Britain Sept. 2, 1943 

